[Chronic hepatitis B: standard of therapy and perspectives]

Infection with the hepatitis B virus (HBV) has much diminished in Italy in the last 25 years; at present, all Italian nationals aged under 36 years are protected from HBV by vaccinal immunity. The problem of the infection has shifted to the immigrants from countries where HBV is still endemic; in this population the prevalence of the infection is high, up to 10% of the immigrants. In the next 5 years the prevalence of HBV is bound to further diminish in the domestic population, for the increment of the age of the subjects protected by mandatory HBV vaccination and for the natural exhaustion of the elderly cohorts of HBsAg carriers which represent the last domestic reservoir of the infection. Most likely, instead, the problem in immigrants will become more important, forcing new strategies to the approach and containment of HBV. Therapy of hepatitis B is not satisfactory; it allows the control of HBV replication and related disease but is not capable of clearing the virus; eradication of the HBsAg is achieved only in few patients. The future target are therapies aimed at eradicating the HBV, not only at containing its replication and disease expression. A miriad new drugs acting directly against functions necessary to the life cycle of the HBV are under study; it is unlikely, however, that they will enter clinical trials in the few years. More promising in the short term, it is the development of prodrugs of antivirals currently in use, of which tenofovir alafenamide (TAF), the prodrug of tenofovir, is the prototype, entering soon into therapeutic routine.